Density control system for block-making apparatus

ABSTRACT

An automatic block-forming apparatus in which the blocks are formed by compressing the block material in a mold box until the material takes the shape of the mold cavity. The compression stroke is automatically timed and compared each cycle to a range of acceptable times that will result in a block having an acceptable density. If the compression time falls outside of the acceptable time range, a control circuit sounds an alarm and indicates whether more or less material must be fed into the mold box to either increase or reduce the density of the compressed blocks.

C United States Patent 1111 3,604,075

[72] Inventors Frank K. Locke [56] References Cited Hudson, M UNlTED STATES PATENTS Russell-L 2,586,210 2 1952 Corwin 25/41.1 x (by Campbell 2,991,531 7/1961 Gates 25 45 ex u x 3,104,386 9 1963 K1 340 309.1 121 App]. No. 795,778 em [22] Filed Jam 27 19 9 Primary Examiner-J. Spencer Overholser [45] patented Sept 14, 1971 Assistant Examiner-DeWalden W. Jones [73] Assignee Stearns Manufacturing Company, Inc. Glfford Patahdls Flat Rock, Mich.

ABSTRACT: An automatic block-forming apparatus in which [54] igix gfi b FOR BLOCK' the blocks are formed by compressing the block material in a 7 Cl 6 D mold box until the material takes the shape of the mold cavity. rawmg The compression stroke is automatically timed and compared [52] US. Cl 25/41 D, each cycle to a range of acceptable times that will result in a 340/3091, 18/4 P block having an acceptable density. If the compression time [51} B28b 7/00 falls outside of the acceptable time range, a control circuit [50] Field of Search....; 25/413, sounds an alarm and indicates whether more or less material 4111,45, 83, 102, 109, 120; 18/4 P, 23; IMO/309.1,

must be fed into the mold box to either increase or reduce the 309.4 density of the compressed blocks.

'1 w w fl l l l l 1 1 l 4' Mex/Iva 30 i I //4 #540 L ADJUSTIGK! 40 1 1 1 1 l l l 1 (GIVIRUL PATENIEB 8814871 SHEET 1 BF 3 kw YER mum w mm mm WEMK NK ,fl mu Wlfi .r. x w w M a r K J m 0 W W m ATTORNEYS DENSITY CONTROL SYSTEM FOR BLOCK-MAKING APPARATUS BACKGROUND OF THE INVENTION This invention relates to block-forming apparatus and more specifically to a system for controlling the density of the blocks produced by such an apparatus.

The output quality of automatic machines for forming building blocks is usually measured in terms of the material density of the finished block. Acceptable blocks must be within a permissible range of densities. In conventional machines, theblocks are formed by depositing a charge of a compactible block-forming material into an open mold having dimensions corresponding to the finished block. The volume of the charge is greater than the volume of the finished block. A packing head then compresses the contents of the mold to the volume of the block. It has been found that the time for the packing head to compress the material is related to the density of the block. Thus, if the compression time is greater or lesser than a range of times corresponding to an acceptable range of densities, there is respectively, too much or not enough material being deposited in the mold box. Considerable effort has been made toward developing sophisticated systems for feeding a controlled amount of material into the mold box to produce a finished block having an acceptable density. In

general such systems have proven to be unreliable because of their complexity.

SUMMARY The broad object of the present invention is to provide an alarm system for automatically indicating to the operator of an automatic block-forming machine whether or not the blocks being produced by the machine have an acceptable density. If

the blocks are not acceptable, the system indicates whether the operator should increase or decrease the quantity of block forming material being fed into the mold box in order to correct the density. The preferred block-forming apparatus has the usual compression and feed components including an open-topped mold box having a cavity corresponding to the dimensions of the finished block, a feed drawer for transferringa charge of block material from a hopper to the mold box, and a packing head for compressing the contents of the mold box. The quantity of material fed into the mold box is a function of the time the feed drawer is disposed in a feed position over the cavity and can be adjusted to either increase or reduce the feed rate. The mold compression time, i.e. the time it takes the packing head to compress the mold box contents to a given volume varies as the amount of material fed into the mold box. The preferred alarm circuit includes a pair of timers that engage the packing head during its compression stroke.

One timer is actuated during each cycle as the packing head commences its compression stroke and is adjusted for an acceptable minimum" time. If the packing head has not completed its stroke after the minimum time has passed, the

first timer energizes the second timer which is adjusted for a permissible tolerance between the minimum and the maximum compression time that is associated with an acceptable range of block densities.

If the packing head completes its stroke before the :minim um time has elapsed, the alarm circuit energizes a below standard" light, and a horn as it deenergizes the compression time is acceptable and the machine continues the cycle: lf the compression time exceeds the maximum time, the alarm circuit energizes an above standar light and sounds a horn to attract the operatorsattention and to indicate that the feed rate must be reduced.

The preferred alarm system provides a number of advantages over other density control systems because it automatically indicates to the operator an unacceptable operating condition as well as what must be done to correct the condi tion. He corrects the feed discharge rate by merely turning a control knob to adjust the timing of the feed drawer. A skilled mechanic is not necessary to adjust the feed as is the practice with some commercial machines.

Still other advantages of the present invention will become readily apparent to one skilled in the art to which the invention pertains upon reference to the following detailed description.

DESCRIPTION OF THE DRAWINGS I The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which:

FIG. 1 is a schematic diagram of the major components of a typical block-making apparatus;

FIGS. 2 to 5 indicate the motions of the major components during a block-forming cycle; and

FIG. 6 is a schematic view of the preferred electrical alarm circuit.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 to 5, the preferred block-making apparatus comprises a frame, generally indicated at 10 (FIG. 1) having drive means (not shown) for horizontally advancing a pallet 12 to a mold-filling position. A mold box 14 supported on the pallet 12 for vertical motion has a mold cavity 16 corresponding to the dimensions of a finished building block. The mold box 14 is seated on the pallet 12 which blocks the lower side of the cavity 16, however its upper side is open to receive the block material.

Referring to FIG. 1, a feed drawer 18 is supported by the frame 10 for horizontal movement between a fillposition in which it is disposed below a hopper 20 and a dispensing position in which it is over the mold box 14. The feed drawer 18 receives material from the hopper 20 and then transfers it to the mold box 14. A series of agitators 22, driven by a motor (not shown) are rotated when the feed drawer is in its dispensing position in order to dispense a quantity of material into mold cavity 16. The charge of material dispensed is proportional to the period of time the feed drawer is in its dispensing position.

The feed drawer 18 is reciprocated between its fill and its dispensing positions by a feed drawer drive means 24 which may comprise a suitable linkage connected to a reversible drive motor. This is shown diagrammatically in FIGS. 2 and 3. The delay time of the feed drawer, i.e. the period it is in its dispensing position is controlled by an adjustable timer 26 adapted to permit the operator of the machine to manually adjust the feed drawer drive means and thereby control the quantity of material fed into the mold cavity 16 during each cycle.

A packing head 28, mounted above the mold box 14, functions as a means for compressing the block material in the mold box. A drive means 30 moves the packing head 28 between raised and lowered positions in its compression stroke. When the feed drawer 18 has been retracted from its dispensing position, the packing head is lowered in its compression stroke to reduce the volume of the mold box contents to the volume of the building block as shown in FIG. 4. The time the packing head is being moved in its compression stroke varies as the final density of the block since the resistance to the motion of the packing head depends on the density of the material being compressed which in turn depends on the quantity of material in the mold box. W hen the charge of material in the mold cavity 16 is too large, the density of the finished block exceeds an acceptable density which is reflected in a long compression time. Similarly when the charge of material is too small, the density of the block is less sion time.

Upon completion of the compression stroke, as shown in FIG. 5, the mold box 14 is raised from the pallet 12 by suitable apparatus (not shown) to strip the block 32 which is then carried on the pallet 12 to a curing oven. The next pallet 12 is positioned below'the mold box 14 which is lowered to receive a charge of material.

Referring to FIG. 1, an upper height contact 34 carried by the packing head 28 is engageable with an electrical lower height contact 36 which is mounted on the frame 10. The upper contact 34 engages the lower contact 36 in the packing heads lower position, the two contacts forming a switch in a control circuit 38 which through an electrical line 40 is operable to either deenergize or energize the packing head drive 30, the feed drawer drive 24, and various alarm and indicating components mounted on an indicating panel 42.

Now referring to FIG. 6, the alarm components of the control circuit are energized depending upon the compression time of the packing head, i.e., the time it takes for the packing head to move from its upper position to a position in which the contacts 34 and 36 make contact. The contacts 34 and 36 are disposed in a line 44 which connects a pair of power lines 46 and 48, and upon making contact at the conclusion of the packing head's compression stroke, energize a relay coil 50. Relay coil 50, upon closing, energizes a normally open contact 50 A, a normally closed contact 50 B, and a normally open contact 50 C. The control circuit 38 also has a line 52 for energizing a drive circuit 54 which controls the feed drawer drive 24, a circuit 56 which controls packing head drive 20, and a drive circuit 58 for controlling a pallet feed mechanism (not shown).

As the packing head 28 commences its compression stroke, a normally open contact 60 in a line 62 is closed to energize a coil relay 64. A reset button 66 is also connected in the line 62 to provide means for energizing the contact circuit after it has been deenergized.

The relay 64 energizes a normally open contact 64 A, which upon closing seals in the coil 64. The contact 64 A, upon closing, completes an electrical connection through a line 67 to a timer 68 which is adjusted to the minimum acceptable compression time. A normally open switch 68 A is connected to timer 68 and is closed when the timer 68 times out. Closing of switch 68 A completes a circuit through a coil relay 72 which controls normally closed contact 72 A, normally open contact 72 B and normally open contact 72 C.

The energization of the coil relay 72, which occurs upon passage of the minimum compression time, opens contact 72 A in line 76, closes the normally open contact 72 B in line 78, and closes the contact 72 C in line 80. The condition of the control circuit then depends upon whether or not the height contacts 34 and 36 make their connection before the contacts 72 A are opened. If the contacts 34 and 36 are closed first because of a short compression time, a circuit is completed through the line 76 to a coil relay 82 which controls normally open contacts 82 A in line 84, normally closed contacts 82 B in line 78, contacts 82 C in line 86, a normally closed contacts 82 D in the line 52 which directs power to the remainder of the machine. As coil relay 82 is energized, it closes contacts 82 A to make an electrical connection as add-feed light 88 in the line 84 and opens normally closed contacts 82 D to stop operation of the feed drawer 18, the packing head 28 and the pallet feed drive circuit. Energization of relay 82 also closes the contacts 82 to energize an add-feed" alarm horn 90, and opens contacts 82 B to interrupt power to the balance of the control circuit.

lf,however, the height contacts 34 and 36 close after the contacts 72 A are opened, coil relay 82 is not energized and an electrical circuit is completed through the line 78 to energize a second timer 92 which is adjusted for the difference between the minimum and the maximum compression times during which an acceptable block density will normally be produced. The timer 92 controls a normally open switch 92 A in line 94, and a normally closed switch 92 B in line 80.

The next condition of the alarm circuit depends on whether the height contacts 34 and 36 engage one another before or after the timer 92 has timed out. If the height contacts 34 and 36 make contact after coil relay 72 is energized, but before the timer 92 has timed out, coil relay 96 is energized by a connection through line 80. Relay 96 which controls normally closed contacts 92 A in line 84, normally open contacts 96 E in line 98 and normally open contacts 96 C in line 94 so that when energized relay 96 energizes an in-tolerance" light 100. Light 100 indicates that the actual compression time corresponds to an in-tolerance block density.

In addition, energization of the coil 96 opens the line 94 to block a signal to a coil relay 102 which controls contacts 102 A in a line 104. If the height contacts 34 and 36 close after timer 92 has timed out, coil relay 102 is energized to close contact 102 A which seals in the relay 102 and energizes a subtract feed" light 106 in line 108. Light 106 indicates to the operator that less feed is necessary. The normally open contact 102 B in line 110 is also closed so as to energizean alarm horn 112. Thus when blocks having an unacceptable density are being molded, the operator, depending upon the particular signals that are energized, makes an appropriate adjustment in the feed rate and then pushes the reset button 66 to restore the circuit to its normal condition and the machine to its automatic operation.

Referring again to FIG. 1, it can be seen that the various visual alarm signals are displayed on the panel 42 to provide an immediate indication of the nature of the adjustment necessary to correct the block density. Normally if the blocks are acceptable, the in-tolerance light 100 is energized. lf, however, the density if less than acceptable, the add-feed light 88 is energized, the operator increases the feed rate by adjusting a control knob 114 to increase the time the feed drawer is in its dispensing position over the mold box 14. If, however, the subtract-feed light 106 is energized, the operator then knows that he has to adjust the control knob 1 14 to reduce the time the feed drawer 18 is in its dispensing position to reduce the feed rate.

Thus it can be seen that we have described in detail a density control system for a block-forming machine in which various alarms are energized, depending upon the compression time, to indicate when the blocks have a density that is greater or lesser than an acceptable range, and suitable indicators are energized to indicate the appropriate adjustment that must be performed on the machines operation.

Having described our invention what is claimed is:

I. In a block-forming apparatus, the combination comprising a mold box adapted to receive a charge of a block-forming material into a mold cavity, feed means for depositing a selectively variable quantity of block material into the mold cavity, said quantity of block material having a volume greater than a block of a predetermined volume; a packing head movable in a compression stroke in which it compresses the block material in the mold cavity to said predetermined block volume in a compression time that varies as the quantity of the block material deposited into the mold cavity by the feed means and thus the density of the block; control means responsive to the motion of the packing head in its compression stroke for indicating wherever the compression time is within a predetermined range of compression times corresponding to a predetermined range of block densities; and adjustment means connected to the feed means for varying the quantity of block material deposited into the mold cavity to change the block density when the control means indicates that the compression time is outside of the predetermined range of times.

2. The invention as defined in claim 1, in which said control means is operable to electrically energize said apparatus in a continuously operating cycle; and to automatically terminate said continuously operating cycle when said compression time falls outside of the permissible range of times.

3. The invention as defined in claim 1, in which said mold box has an open top for receiving a charge of block material; the packing head is movable in its compression stroke from a raised position above the mold box toward a lowered position in which it engages the material in the mold box; and the control means include a pair of electrical contacts, a first of which is carried by the packing head, the second of which is engaged with the first when the packing head is at the bottom of its stroke, and timing means connected to the contacts for deenergizing the block-making apparatus whenever the contacts are engaged before the passage of a predetermined time interval after the packing head has commenced its stroke.

4. The invention as defined in claim 1, in which control means includes indicator means for automatically indicating whether the quantity of material deposited in the mold cavity must be increased or decreased to provide an appropriate change in block density whenever the compression time is outside of the predetermined range of times.

5. The invention as defined in claim 4, in which said indicating means includes audible alarm means.

6. The invention as defined in claim 1, in which said control means including a first indicator and means for energizing said first indicator when the compression time is less than the permissible range of times; a second indicator and means for energizing the second indicator when the compression time is greater than the permissible range of times whereby the operator of the apparatus is informed whether to increase or decrease the quantity of material deposited in said mold box depending upon the condition of said indicators.

7. The invention as defined in claim 1, in which the control means is operative to deenergize said apparatus whenever the compression time is less than the permissible range of times whereby the operation of the block-forming apparatus is terminated whenever the feed means is not depositing material into the mold cavity.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No September l4,

Inventor(s) Frank K. Locke et a].

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 67, after "empty" insert or and delete "of".

Column 3, line 59, after "connection" delete "as" and insert --an-.

Column 4, line 5, after "contacts" delete the numeral "92" and insert --96--.

Column 4, line 30, after "density" delete "if" and insert --is- Column 4, claim 1, line 59, after "dicating" delete "wherever" and insert -whenever-.

Signed and sealed this 28th day of March 1972.

(SEAL) Attest:

EDWARD M.FIETGHER,JR. Attesting Officer ROBERT GOTTSCHALK Commissioner of Patents DFW 0459) USCOMM-DC 50376-P69 n U 5 GOVERNMENT PRINTING OFFICE I959 0-366-31 

1. In a block-forming apparatus, the combination comprising a mold box adapted to receive a charge of a block-forming material into a mold cavity, feed means for depositing a selectively variable quantity of block material into the mold cavity, said quantity of block material having a volume greater than a block of a predetermined volume; a packing head movable in a compression stroke in which it compresses the block material in the mold cavity to said predetermined block volume in a compression time that varies as the quantity of the block material deposited into the mold cavity by the feed means and thus the density of the block; control means responsive to the motion of the packing head in its compression stroke for indicating wherever the compression time is within a predetermined range of compression times corresponding to a predetermined range of block densities; and adjustment means connected to the feed means for varying the quantity of block material deposited into the mold cavity to change the block density when the control means indicates that the compression time is outside of the predetermined range of times.
 2. The invention as defined in claim 1, in which said control means is operable to electrically energize said apparatus in a continuously operating cycle; and to automatically terminate said continuously operating cycle when said compression time falls outside of the permissible range of times.
 3. The invention as defined in claim 1, in which said mold box has an open top for receiving a charge of block material; the packing head is movable in its compression stroke from a raised position above the mold box toward a lowered position in which it engages the material in the mold box; and the control means include a pair of electrical contacts, a first of which is carried by the packing head, the second of which is engaged with the first when the packing head is at the bottom of its stroke, and timing means connected to the contacts for deenergizing the block-making apparatus whenever the contacts are engaged before the passage of a predetermined time interval after the packing head has commenced its stroke.
 4. The invention as defined in claim 1, in which control means includes indicator means for automatically indicating whether the quantity of material deposited in the mold cavity must be increased or decreased to provide an appropriate change in block density whenever the compression time is outside of the predetermined range of times.
 5. The invention as defined in claim 4, in which said indicating means includes audible alarm means.
 6. The invention as defined in claim 1, in which said control means including a first indicator and means for energizing said first indicator when the compression time is less than the permissible range of times; a second indicator and means for energizing the second indicator when the compression time is greater than the permissible range of times whereby the operator of the apparatus is informed whether to increase or decrease the quantity of material deposited in said mold box depending upon the condition of said indicators.
 7. The invention as defined in claim 1, in which the control means is operative to deenergize said apparatus whenever the compression time is less than the permissible range of times whereby the operation of the block-forming apparatus is terminated whenever the feed means is not depositing material into the mold cavity. 